Starting device for carburetors



June 10, 1941. L. BECK STARTING DEVlCE FOR CARBURETORS 2 Sheets-Sheet 1 Filed Nov. so. 1938 June 10, 1941. L. BECK I STARTING DEVICE FOR CARBURETORS 2 Sheets-Sheet 2 Filed Nov. 30, 1938 Patented June 10, 1941 2,245,139 STARTING DEVICE FOR CARBURETORS Ludwig Beck, Berlin-Zehlcndorf, Germany Appiicaticn November 30, 1938, Serial No. 243,957 In Germany December l, .1937

4 Claims.

This invention relates to a starting device for injection carburetors which insures reliable starting even if the motor is very cold and which is distinguished by its particular simplicity. Another advantage of the carburetor designed according to this invention is the fact that it can be utilised also as an accelerating device and can be equipped comparatively easily with an automatic thermic control.

According to the-invention there are provided two air passages connected to the main mixing chamber behind thecarburetor throttle and having different widths, the sectional area of which can be controlled simultaneously by a valve device so that one air passage is closed while the other air passage is opened and vice versa, and of which air passage the narrower one is connected to a fuel well ahead of the point where it terminates in the mixing chamber. The valve device mentioned is designed in such a manner that the narrower air passage, the orifice of. which can be designed as an injection nozzle, communicates with the atmosphere through its entire sectional area when the motor runs in normalmanner. For starting, the narrower air passage is disconnected from the atmosphere by means of the said valve device. There then arises a pressure below atmospheric pressure in the fuel well connected with said air passage so that fuel is drawn in and is injected into the mixing chamber through its nozzle-shaped orifice. At the same time, by opening the second, materially larger air passage, a sufficient amount of combustion air is introduced into the mixing chamber. In this manner the most favorable ratio of mixture for starting the carburetor is insured in the mixing chamber.

The invention is illustrated diagrammatically and by way of example by the accompanying drawings of which Figure 1 is a side-view of a carburetor embodying the principles of the invention,

Figure 2 is a front-view partly in cross-section of the carburetor shown in Figure 1,

Figure 3 a plan of an improved starting device, the important parts being shown in section,

Figure 4 is a longitudinal section through a carburetor equipped with a manually operable starting device designed according to the invention, parts not necessary for the understanding of the invention having been omitted,

Figure 5 shows a carburetor assembly similar to that according to the preceding figures combined with a thermostatic device for automatic control of the starting valve, wherein the control device is mounted upon the exhaust pipe of an engine and connected to the main carburetor through suitable conduits indicated by dot and dash lines,

Figures 6 and '7 are a side view and a partial front View of a modified thermostatic control device according to Figure 5 embodying means to enable both manual and automatic control of the starting valve.

As best seen from Figure 4, a nozzle 5 extends into the mixing chamber l equipped in the usual manner with a Venturi tube 2 and the main nozzle 3, said nozzle 5 being located behind the throttle denoted by numeral i. The nozzle 5 terminates at its other end in a chamber 6 from which it is separated by a valve disk I. This disc l is supported by the cover i of the chamber 5 by means of a bolt 8. An adjustable valve H3 serves to establish communication between the chamber 5 and the outer air. The disk "I is pressed against the inner surface of the chamber e by means of a spring ii encircling the bolt 8. The bolt 8 together with the disk I can be turned about its axis by means of a lever E2. The cover 9 and the adjusting lever 52 are more clearly shown in Fig. 1.

The air passage of the nozzle 5 communicates with the fuel passage or well Hi by means of a transverse bore 43 lying above the fuel level d-b. The well I4 is constructed in a known manner, as a dipping-tube accumulator or storage receptacle and is tightly closed at its top by a screw l5. When the disk 1 disconnects the nozzle 5 from the air chamber i5, fuel will be drawn in through the nozzle. As the nozzle is designed as an injection nozzle, the fuel will be finely distributed or atomised when it enters into the mixing chamber.

Besides the air passage formed by the nozzle 5, another air inlet it, Figure 3, which has a substantially larger cross-sectional area, extends from the air chamber 6 into the mixing cham her i at a point on the engine side of the throttle 4. The disk 1 extends also over the entrance to this second air passage and is provided with two apertures H and 58, Figure 2, arranged opposite to one another. tor the disk I is in the position shown in Fig. 2, in which position it disconnects the air passage Hi from the chamber 6 and permits unimpeded access of the air into the nozzle 5. No fuel is, therefore, drawn in from the well 14. The small quantity of air entering through the nozzle 5 affects the normal actionof the carburetor only insofar as it promotesa thorough whirling of the At normal running of the mo fuel mixture. For starting, the disk '5 is turned to the right by about 30 so that it assumes the position shown in Figure 3 in which it disconnects the nozzle 5 from the air chamber 6. As a result thereof, a pressure below atmospheric pressure arises in the channel 53 in such a manner that fuel is drawn into the mixing chamber through the nozzle 5. Simultaneously therewith the disk 1 establishes a communication between the air passage and the air chamber 6 so that a sufficient quantity of combustion air passes into the mixing chamber. The fuel and the air enter tangentially into this chamber whereby a particularly fine atomisation of the fuel is obtained.

In order to actuate the starting device all that is necessary is to turn the lever l2 to the right, Figure 1. This can be effected in the usual man ner by means of a cable and pulley connection or the like. When a pull is exerted on the cable while the car is running, the device acts as an accelerating device in that the fuel supply and the air admission are simultaneously increased.

A carburetor provided with an automatic thermic control can be obtained by providing a helically wound bimetallic wire which turns to the right when the bolt 8 becomes hot. As, however, the carburetor is subject, as a rule, whenthe motor is running, only to comparatively slight variations of temperature, it is recommendable to provide for an exchange of heat between the thermically operated valve device controlling the two air passages and a part of the motor that is subject to the strongest variations of temperature such as for instance the exhaust pipe and to connect, in addition thereto, the air passages 5 and IS with the valve through suitably arranged pipes or conduits.

In this constructional form the starting nozzle 2| which is designed as an injection nozzle is introduced into the carburetor channel l9 behind the throttle 2B. The starting nozzle communicates with the chamber 22 in which terminate the pipe 23 of the fuel supply, and the hose branch 24 constituting the air supply member. In the same part of said channel is terminates the hose branch 25. The members 25 and 25 are connected by means of conduits (indicated by dotted lines) with connecting members 26 and 27, respectively, pertaining to the thermally controlled valve device illustrated in Fig. 6. The latter consists of a metal-block. 28 attached to the exhaust pipe 30 by means of a clip 29, thus being in heat conducting connection with the pipe 3!]. The two air passages 31 and 32 extend through the block 28 and terminate at the valve inlets 33 and 34, respectively, arranged directly opposite to one another. It is advantageous to provide in the passage formed by the members 25, 27, 32 and 34 an exchangeable nozzle 35 in order to adapt the starting device to various requirements.

The two air inlets 33 and 34 are controlled by means of a double-sided valve fiap 3G affixed to a bimetallic strip 31. When the motor is cold, the valve closes, in the manner shown, the inlet 33 leading to the starting nozzle 2|. When the cold motor is started, then a strong pressure below atmospheric pressure arises in the chamber 22 so that fuel is drawn from the well pipe 23 and is introduced into the mixing chamber through the injection nozzle 2|. Normally the fuel level in the chamber 38 and well pipe 23 is at a position as shown at 0-12 to insure an adequate supply when the motor is started. Simultaneously therewith, an accurately determined quantity of combustion air is drawn in through the open aperture 34 and the air passage 35, 32, 21, 25 so that the motor starts with certainty. After this has taken place, the motor will receive only that quantity of fuel which passes through the nozzle 39 and is atomised by the air entering through the nozzle 40.

As the temperature of the motor increases, the bimetallic strip 2|) will bend upwardly until it has arrived in the position indicated in dotted lines. In this position the strip has completely closed the air inlet 34, whereas the air passage 33 is now completely open and there flows now such a quantity of air into the chamber 22 that there is no pressure below atmospheric pressure in this chamber, that is to say, no pressure sumcient to draw fuel from the pipe 23. The starting nozzle is now no longer able to operate as a fuel supplying member. At the same time due to the closure or the air inlet kit, a. braking erl'ect is imposed upon the motor in the usual manner when fuel is withdrawn whereupon the fuel mixture is determined exclusively by the main injection nozzle 4|.

According to a further improvement, in order to render it possible to accelerate the speed during running when the motor has its working temperature, a cam 2, Figures '1 and 8, is provided by me aid or which the bimetallic strip 3? may be depressed by pulling a cable or the like 43 at the instrument board. In this case the Valve disk 36 closes the aperture 33 and opens the aperture 34 so that a strong excess of fuel can be drawn in through the starting nozzle 2| independently of the existing temperature, while simultaneously the necessary quantity of air for the combustion of the additional amount oi fuel is drawn into the carburetor channel through the passage, 3433-32-2i--25. In order, in this case, to prevent the adjusting strip 31 from bending the strip is either elastically supported at 44 or is equipped with an elastic intermediate piece.

If air is introduced into the carburetor channel behind the Venturi tube, according to this invention, the amount of fuel supplied by the main nozzle may be, in some cases and when the mixing throttle is open, reduced so strongly that the additional amount of fuel supplied cannot be compensated. In such a case the starting device provided for producing an additional acceleration can be used only if the valve body -i, Figures 1 1, is so designed that it interrupts the supply of air to the nozzle 5 already in a middle position without permitting at this position now the access of air to the passage It. If for this middle position an indicator is provided, the starting device, as described, acts as an accelerating device as soon as it is adjusted to the respective middle position. Alternatively it is possible to provide an additional manually controllable valve for throttling the supply of air to the air passage connected with the fuel supply without throttling the valve common to the said air passages. This can be obtained, for instance, by means of the adjusting valve l0, Figure 4, which for this purpose may be equipped with an adjusting lever from which a cable or the like extends to the instrument board. If the valve iii is closed, the nozzle 5 will obviously draw in fuel solely if the valve 7 is in its proper position, Figure 2.

What I claim is:

1. The combination With a carburetor assembly for internal combustion engines having a mixing chamber, a main fuel nozzle and a throttle valve, of an auxiliary fuel supply passage terminating in the part of said mixing chamber on the engine side of said throttle valve, a first air passage terminating in said auxiliary fuel passage, a second air passage of large crosssection relative to said auxiliary fuel passage terminating in the part of said mixing chamber on the engine side of said throttle valve, and valve means for closing the air supply through said first air passage While admitting air through said second air passage and vice versa.

2. The combination with a carburetor assembly for internal combustion engines having a mixing chamber, a main fuel nozzle and a throttle valve, of an auxiliary fuel nozzle projecting into the part of said mixing chamber on the engine side of said throttle valve, a fuel supply passage connected to said auxiliary nozzle, a first air passage terminating in said fuel supply passage, a second air passage of large crosssection relative to said aum'liary fuel pas-sage terminating in the part of said mixing chamber on the engine side of said throttle valve, and valve means for closing the air supply through said first air passage while admitting air through said second air passage and vice versa.

3. The combination with a carburetor assembly for internal combustion engines having a mixing chamber, a main fuel nozzle and a throttle valve, of an auxiliary fuel supply passage terminating in the part of said mixing chamber on the engine side of said throttle valve, a first air passage terminating in said auxiliary fuel passage, a second air passage of large crosssection relative to said auxiliary fuel passage in the part of said mixing chamber on the engine side of said throttle valve, valve means for interrupting the air supply by said first air passage while admitting air through said second air passage and vice versa, and a thermostatic device responsive to the engine temperature arranged to control said valve means to close said first air passage and simultaneously open said second air passage While the engine is cold and to open said first air passage and simultaneously close said second air passage while the engine is hot.

i. The combination With a carburetor assembly for internal combustion engines having a mixing chamber, a main fuel nozzle and a throttle valve, of an auxiliary fuel supply passage terminating in the part of said mixing chamber on the engine side of said throttle valve, a first air passage terminating in said auxiliary fuel passage, a second air passage of relatively large cross-section relative to said auxiliary fuel passage in the part of said mixing chamber on the engine side of said throttle valve, Valve means for interrupting the air supply through said first air passage while admitting air through said second air passage and vice versa, 21- thermostatic device responsive to the engine temperature arranged to control said valve means to close said first air passage and simultaneously open said second air passage While the engine is cold and to open said first air passage and simultaneously close said second air passage while the engine is hot, and manual adjusting means for said thermostatic device to control said air passages substantially independently of the engine temperature.

LUD WIG BECK. 

